Apologies if this has been posted previously but, if you want some ideas for details and scenery or you just want to get lost down a rabbit hole of an incredible collection of railroad photographs, you might check the John W. Barriger III National Railroad Library Collection. Primarily appears to cover the 20s through the 60s and most of the major railroads of the era are represented as well as many bygone shortlines. Note that these are not strictly trains and roster shots, but rather lots of simple images of railroad tracks, facilities, stations, signals, and views. Many of the images are presented reversed but some of the mundane details you can pick up are impressive. I just spent an hour going through about a third of the Rock Island album:
https://www.flickr.com/photos/barrigerlibrary/albums
Enjoy!
redrockbill
